Multi-protocol interchip interface

ABSTRACT

An interface between radios supporting different air interfaces is disclosed that avoids some of the costs and disadvantages associated with inter-radio interfaces in the prior art. The present invention enables the needed coordination across multiple wireless protocols, such as 802.11 and Bluetooth, by providing a communication link spanning different integrated circuits when each radio is on a separate integrated circuit. This low cost, low complexity link can be added to standard integrated circuits produced by individual companies without adding appreciably to the overall cost of the integrated circuits.

CROSS- REFERENCE TO RELATED APPLICATIONS

The present application is a broadening reissue application of U.S.patent application Ser. No. 11/429,556, filed May 5,2006 (now U.S. Pat.No. 7,373,172, granted May 13, 2008), which is a continuationapplication of U.S. patent application Ser. No. 10/444,383, filed May23, 2003 now U.S. Pat. No. 7,072,616. U.S. patent application Ser. No.10/144,383

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of:

-   -   1. U.S. provisional application Ser. No. 60/409,356, filed Sep.        9, 2002, entitled “A Mechanism For Collaboration And        Interference Prevention Between 802.11 And Bluetooth Using The        802.11 Power Save Mechanism,” and    -   2. U.S. provisional application Ser. No. 60/411,848, filed Sep.        18, 2002, entitled “Coordinating A Plurality Of Medium Access        Control Protocols That Share A Common Communications Channel,”        both of which are also incorporated by reference.

The following patent application is incorporated by reference:

-   -   1. U.S. patent application Ser. No. 10/444,519, entitled        “Coordination of Competing Protocols”.

FIELD OF THE INVENTION

The present invention relates to telecommunications in general, and,more particularly, to a telecommunications terminal with two radiosoperating in accordance with two protocols that might interfere witheach other.

BACKGROUND OF THE INVENTION

FIG. 1 depicts a schematic diagram of a portion of wirelesscommunication system 100 in the prior art. Wireless communication system100 comprises wireless terminals 101-1 through 101-6, all communicatingwith each other by using one or more air interfaces in the same, sharedfrequency band. As an example, IEEE 802.11 (i.e., “802.11”) wirelessterminals 101-1, 101-2, and 101-4 communicate using an 802.11 airinterface, Bluetooth wireless terminals 101-5 and 101-6 communicateusing a Bluetooth air interface, and 802.11/Bluetooth wireless terminal101-3 communicates using either an 802.11 or a Bluetooth air interface.

As depicted in FIG. 1, wireless terminal 101-2 is transmitting a signalwith wireless terminal 101-3 as the intended recipient. Also, wirelessterminal 101-6 is transmitting a signal with wireless terminal 101-5 asthe intended recipient. Wireless terminals 101-2 and 101-6 can transmitsimultaneously, although in order to do so, either (1) their respectivetransmissions have to be coordinated, or (2) wireless terminals 101-2and 101-6 have to be situated far enough apart from each other tominimize interference. If, however, a wireless terminal supports two airinterface protocols (e.g., wireless terminal 101-3, etc.), a mechanismmust exist to prevent interference (i.e., the effect of two radiostransmitting simultaneously in the same frequency band), since spatialseparation of two air interfaces within the same wireless terminal isnot an option.

In accordance with a first technique in the prior art, FIG. 2 depicts ablock diagram of the salient components of wireless terminal 101-3.Wireless terminal 101-3 comprises host 201, A/B switch 202, 802.11 radio203, Bluetooth radio 204, antenna switch 205, and antenna 206. Host 201comprises a microprocessor. At any given time, host 201 communicateswith 802.11 radio 203 or Bluetooth radio 204, both not both, by means ofA/B switch 202. 802.11 radio 203 communicates in accordance with the802.11 air interface, and Bluetooth radio 204 communicates in accordancewith the Bluetooth air interface. Antenna switch 205 directs a signal tobe transmitted to antenna 206 from either 802.11 radio 203 or Bluetoothradio 204. Antenna switch 205 also directs a received signal fromantenna 206 to either 802.11 radio 203 or Bluetooth radio 204. Antennaswitch 205 is coordinated with A/B switch 202.

The first technique in the prior art controls contention for the sharedfrequency band through A/B switch 202. In addition to providingcontention-free access to the shared frequency band, the first techniqueprovides a low-cost solution. As a disadvantage, however, the airinterface in use must remain in either 802.11 or Bluetooth mode forrelatively long periods of time. Also, contention resolution requiresmanual intervention on the part of a user whenever wireless terminal101-3 has to make a transmission over the air interface that is notpresently active. Finally, the inactive air interface might miss atransmission by some other wireless terminal.

In accordance with a second technique in the prior art, FIG. 3 depicts ablock diagram of wireless terminal 101-3. Wireless terminal 101-3comprises host 301, 802.11 radio 302, Bluetooth radio 303, antennaswitch 304, and antenna 305. Host 301 comprises a microprocessor. At anygiven time, host 301 communicates with 802.11 radio 302 or Bluetoothradio 303, but not both, by means of an internal switch. Typically, theinternal switch requires the user of wireless terminal 101-3 to selectthe air interface to be used (e.g., from a menu, etc.). Alternatively,host 301 chooses between the air interfaces based on the type ofcommunication it needs to send or expects to receive. 802.11 radio 302communicates in accordance with the 802.11 air interface, and Bluetoothradio 303 communicates in accordance with the Bluetooth air interface.Antenna switch 304 directs a signal to be transmitted to antenna 305from either 802.11 radio 302 or Bluetooth radio 303. Antenna switch 304also directs a received signal from antenna 305 to either 802.11 radio302 or Bluetooth radio 303. Antenna switch 304 is coordinated with theselection of the air interface.

The second technique in the prior art integrates the switch into host301, so the intervention by the user is more convenient, even though theintervention is still possibly manual. In addition to providingcontention-free access to the shared frequency band, the secondtechnique provides a more convenient way of allowing the user to changebetween air interfaces. As a disadvantage, however, the air interface inuse must remain in either 802.11 or Bluetooth mode for relatively longperiods of time. Also, contention resolution still possibly requiresmanual intervention on the part of a user whenever wireless terminal101-3 has to make a transmission over-the air interface that is notpresently active. Finally, the inactive air interface might miss atransmission by some other wireless terminal.

In accordance with a third technique in the prior art, FIG. 4 depicts ablock diagram of wireless terminal 101-3. Wireless terminal 101-3comprises host 401, 802.11/Bluetooth radio 402, antenna switch 403, andantenna 404. Host 401 comprises a microprocessor. Host 401 maintains aninterface with the 802.11 part of 802.11/Bluetooth radio 402 and aninterface with the Bluetooth part of 802.11/Bluetooth radio 402.802.11/Bluetooth radio 402 is a single integrated circuit thatcommunicates in accordance with the 802.11 air interface and with theBluetooth air interface. 802.11/Bluetooth radio 402 coordinatestransmissions to some extent between its 802.11 part and its Bluetoothpart. Antenna switch 403 directs a signal to antenna 404 to betransmitted from either the 802.11 part of 802.11/Bluetooth radio 402 orthe Bluetooth part of 802.11/Bluetooth radio 402. Antenna switch 403also directs a received signal from antenna 404 to either the 802.11part of 802.11/Bluetooth radio 402 or the Bluetooth part of802.11/Bluetooth radio 402.

In the prior art, approaches of integrating and dynamically coordinatingmultiple wireless protocols on a single platform have focused onintegration into a single integrated circuit. This control necessitatescoordinating the contention for the same frequency band between the twoair interfaces. If the two air interface protocols are 802.11 andBluetooth, the control must be imposed on the two air interfaces, sincethere is no standardized interoperability between the two air interfaceprotocols. When the individual wireless technologies, however, are on arapid evolutionary path, “same chip” integration can increase cost andcan cause the integrated circuit development to lag behind that ofseparate circuits. Also, the market demand for a dual-interface solutionwithin a single integrated circuit can be considerably smaller than thedemand for either integrated circuit supporting a single protocol only(i.e., 802.11 or Bluetooth, but not both). Furthermore, even same chipintegration by itself does not inherently guarantee a tight, efficientcontention control between the two air interfaces.

Therefore, the need exists for multiple radios supporting different airinterface protocols, possibly on separate integrated circuits, tocoordinate the use of a shared frequency band.

SUMMARY OF THE INVENTION

The present invention is an interface between radios supportingdifferent air interfaces that avoids some of the costs and disadvantagesassociated with inter-radio interfaces in the prior art. The presentinvention enables the needed coordination across multiple wirelessprotocols, such as 802.11 and Bluetooth, by providing a communicationlink spanning separate integrated circuits where each integrated circuitcomprises a different radio. This low cost, low complexity link can beadded to standard integrated circuits made by individual producerswithout adding appreciably to the overall cost of the integratedcircuits.

In some embodiments of the present invention, the interface betweenradios is present as part of a computer that comprises a host processorin addition to the multiple radios. One variation of the computer is awireless terminal, which is used to transmit and receive data blocksover the air. In some other embodiments, the interface between radios ispresent as part of a multi-radio card that plugs into a computer. Insome other embodiments, the interface between radios is described asbeing part of a single radio.

The illustrative embodiment comprises a radio comprising: achannel-access controller for communicating in accordance with a firstair interface, wherein the channel-access controller transmits a firstset of signals to a collateral radio, the first set of signalscomprising a first transmitting indication signal, a first receivingindication signal, and a first idle indication signal, and receives asecond set of signals from the collateral radio, the second set ofsignals comprising a first transmit inhibit signal; and a multi-radiohost interface, wherein the multi-radio host interface communicates thecontents of a first data block associated with the first air interfaceto the channel-access controller when the first data block is receivedfrom a host interface bus, and communicates the contents of a seconddata block associated with the second air interface to the collateralradio when the second data block is received from the host interfacebus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic diagram of wireless telecommunications system100 in the prior art.

FIG. 2 depicts a block diagram of a dual protocol wireless terminal thatuses a first technique in the prior art.

FIG. 3 depicts a block diagram of a dual protocol wireless terminal thatuses a second technique in the prior art.

FIG. 4 depicts a block diagram of a dual protocol wireless terminal thatuses a third technique in the prior art.

FIG. 5 depicts a block diagram of wireless terminal 500 in accordancewith the first illustrative embodiment of the present invention.

FIG. 6 depicts a block diagram of multi-radio card 600 in accordancewith the second illustrative embodiment of the present invention.

FIG. 7 depicts a diagram of the salient components of radio 502-1 inaccordance with the third illustrative embodiment of the presentinvention.

FIG. 8 depicts a block diagram of wireless terminal 800 in accordancewith the fourth illustrative embodiment of the present invention.

FIG. 9 depicts a graph of signals transmitted and theirinterrelationship in the illustrative embodiment of the presentinvention.

FIG. 10 depicts a diagram of the salient components of radio 502-1 inaccordance with another variation of the third illustrative embodimentof the present invention.

DETAILED DESCRIPTION

FIG. 5 depicts a block diagram of wireless terminal 500 in accordancewith the first illustrative embodiment of the present invention.Wireless terminal 500 is a computer that supports two distinct wirelessair interface protocols concurrently for the purpose of sending andreceiving data over the air on a shared frequency band. The frequencyband, when used for communications purposes, is also referred to as a“communications band,” comprising one or more “channels” ofcommunication. The object referred to generically as a “data block”conveys data across a transmission medium (e.g., air, wire, etc.). Adata block constitutes a message, in which the message typicallycomprises a header part and the data in a payload part. A data block canbe also referred to as a “frame” or as a “packet.” The term “frame,” asis known in the art, is commonly used in an IEEE 802.11 protocol contextwhen referring to the medium access control data blocks that arecommunicated across over the air. The term “packet,” as is known in theart, is commonly used in a Bluetooth protocol context when referring tothe data blocks that are communicated over the air.

A wireless telecommunications terminal, or “wireless terminal,” asdescribed in this specification (e.g., wireless terminal 500, etc.), isa type of telecommunications terminal. The wireless protocols supportedby wireless terminal 500 can be, for example, 802.11 and Bluetooth.Wireless terminal 500 comprises host 501, radio 502-1, radio 502-2,antenna switch 503, and antenna 504, interconnected as shown.

Host 501 is a computing platform (e.g., laptop, workstation, wirelessterminal, etc.) comprising a general-purpose or special-purposeprocessor that is capable of storing data into a memory, retrieving datafrom a memory, and executing programs stored in a memory. The memoryconstituting host 501 might be random-access memory (RAM), flash memory,disk drive, etc. Host 501 processes higher-layer applications that usedata that are transmitted over the air and data received over the air.Alternatively, host 501 can be the motherboard of a computer comprisinga processor. Host 501 provides overall control of wireless terminal 500,and the remainder of wireless terminal 500 provides the wirelesscommunication function of host 501. It will be clear to those skilled inthe art how to make and use host 501.

Host 501 also comprises an output device and an input device. The outputdevice (e.g., display, speaker, etc.) is a transducer that receivessignals from the processor and converts the received signals to anoutput signal (e.g., visual, auditory, etc.) in well-known fashion. Theinput device receives input from a user and sends the input to theprocessor. As is well-known in the art, the input device can take on avariety of forms, such as a keypad, pressure-sensitive touch screen,etc.

Radio 502-1 provides the channel-access control for communicating inaccordance with a first air interface (e.g., 802.11, etc.). Radio 502-1provides this service for data blocks arriving from host 501 via hostdata link 506 that are to be transmitted over the air and fordata-blocks arriving from antenna switch 503 via path 510-1-1 that areto be sent to host 501. Radio 502-1 also receives data blocks from radio502-2 and transmits data blocks to radio 502-2. Radio 502-1 exchangesdata blocks with radio 502-2 via collateral radio data link 507, whichwill be described later. Radios 502-1 and 502-2 comprise a receivingfunction and a transmitting function and, as such, are transceivers.

Radio 502-1 receives signals from radio 502-2 and transmits signals toradio 502-2. Radio 502-1 exchanges signals with radio 502-2 viasignaling link 508-1, a bus comprising M lines, and signaling link508-2, a bus comprising N lines. Signaling links 508-1 and 508-2 will bedescribed later.

Radio 502-1 interfaces with host 501 through host data link 506. Hostdata link 506 is a peripheral bus providing signaling, messaging, andcontrol between those devices connected to the bus. It will be clear tothose skilled in the art how to make and use the bus constituting hostdata link 506. In the illustrative embodiment, host 501 is one suchdevice connected to the bus, and radio 502-1 is another device. Radio502-1 can interface with the bus mechanically, as well as electrically,through a removable circuit card designed for such an application.Alternatively, radio 502-1 can be hardwired directly to host 501 via thebus constituting host data link 506. Examples of standardized bussesinclude PCI, MiniPCI, and CardBus, all well known in the art. It will beclear to those skilled in the art how to make and use an interface thatconstitutes host data link 506.

Radio 502-2 provides the channel-access control for communicating inaccordance with a second air interface (e.g., Bluetooth, etc.). Radio502-2 provides this service for data blocks arriving from host 501—viahost data link 506, radio 502-1, and collateral radio data link 507—tobe transmitted over the air and for data blocks arriving from antennaswitch 503 via path 510-2-1 to be sent to host 501. Radio 502-2exchanges data blocks with radio 502-1 via collateral radio data link507.

Radio 502-2 receives signals from radio 502-1 and transmits signals toradio 502-1. Radio 502-2 exchanges signals with radio 502-1 viasignaling link 508-1 and signaling link 508-2. Each of radios 502-1 and502-2 might or might not constitute its own integrated circuit.

Antenna switch 503 exchanges signals with radio 501-1 via paths 510-1-1and 510-1-2, with radio 502-2 via paths 510-2-1 and 510-2-2, and withantenna unit 504. Antenna switch 503 enables antenna unit 504 to beshared, or switched, between radios 501-1 and 502-2, reducing therequired number of antennas. Antenna unit 504 provides coupling fortransmitted and received signals between antenna switch 503 and the air.Antenna unit 504 can consist of a single antenna or it can consist ofmultiple antennas (e.g., one antenna for transmit, two antennas forreceive, etc.). Antenna unit 504 can support receive diversity, transmitdiversity, or both. Radio 501-1, radio 502-2, or host 501 can controlthe antenna switching. FIG. 5 depicts radio 501-1 providing control ofantenna switching via path 511-1. It will be clear to those skilled inthe art how to make and use antenna switch 503 and antenna unit 504. Itwill also be clear to those skilled in the art how to make and use awireless terminal (e.g., wireless terminal 500, etc.) without antennaswitch 503.

Collateral radio data link 507 provides a path through which radio 502-2exchanges data blocks with host 501. Essentially, collateral radio datalink 507 provides the host interface for radio 502-2. This“daisy-chaining” of host 501, radio 502-1, and radio 502-2 is necessary,since multiple integrated circuits with host interfaces that use certainbus standards, such as PCI, cannot be located on the same card becauseof the loading requirements of the bus. PCI, however, supports amultiple function model, in which more than one logical host interfaceis combined into a single physical integrated circuit. Radio 502-1 usesthe ability to host more than one logical host interface and usescollateral radio data link 507 to provide radio 502-2 with access tohost 501. It will be clear to those skilled in the art how to host morethan one logical host interface for a given physical interface.

FIG. 6 depicts a block diagram of wireless terminal 600 in accordancewith the second illustrative embodiment of the present invention.Wireless terminal 600 supports two distinct wireless air interfaceprotocols concurrently. The wireless protocols supported by wirelessterminal 600 can be, for example, 802.11 and Bluetooth. Wirelessterminal 600 comprises host 501, radio 502-1, radio 502-2, antennaswitch 503, and antenna unit 504, interconnected as shown.

Radio 502-1, radio 502-2, antenna switch 503, antenna unit 504, andprinted circuit board 602 constitute multi-radio card 601. Each ofradios 502-1 and 502-2 might or might not constitute its own integratedcircuit. Multi-radio card 601 is mechanically separable from host 501and is electrically connected to host 501 using a card bus standard, inwell-known fashion. The set of possible standards comprises PCI,MiniPCI, and CardBus. Printed circuit board 602, constitutingmulti-radio card 601, plugs into a card bus interface that electricallyconnects host 501 and radio 502-1, and can be physically removed fromthat interface as needed. It will be clear to those skilled in the arthow to make and use printed circuit board 602 as part of multi-radiocard 601.

The relationship and interaction between the elements depicted in FIG. 6differ from that in FIG. 5 only in that the elements constitutingmulti-radio card 601 are mechanically separable from (i.e., nothardwired to) host 501. Elements common to both FIGS. 5 and 6 have beendescribed above.

FIG. 7 depicts a block diagram of radio 502-1 in accordance with thethird illustrative embodiment of the present invention. As is well knownin the art, radio 502-1 might or might not constitute its own integratedcircuit. Channel-access controller 701 provides the medium accesscontrol (MAC) functionality for communicating in accordance with a firstair interface (e.g., 802.11, etc.). Note that the term “medium accesscontrol,” as used in this specification, denotes the functionality thatdetermines which wireless terminal transmits next on a multi-access(shared) channel, constituting a communications band, for a given airinterface. Channel-access controller 701 accepts host data frommulti-radio host interface 702 via path 711. It provides data from host501 to baseband controller 703 via path 712 for preparation fortransmission. Channel-access controller 701 also provides data receivedover the air from baseband controller 703 via path 712 to host 501through path 711 and multi-radio host interface 702. Channel-accesscontroller 701 can track whether it has control or radio 502-2 hascontrol of the frequency band at any given moment. Consequently,channel-access controller 701 can control antenna switching at antennaswitch 503 via path 511-1. Alternatively, channel-access controller 701can operate uninformed of the status of radio 502-2.

Channel access controller 701 can pass to radio 502-2 via signaling link508-1 information representative of receiver 704-1 and transmitter705-1, received through path 715. Channel access controller 701 can passto receiver 704-1 and transmitter 705-1 via path 715 informationrepresentative of radio 502-2, received through signaling link 508-2. Itwill be clear to those skilled in the art how to make and usechannel-access controller 701.

In accordance with the illustrative embodiment of the present invention,multi-radio host interface 702 provides the interface between host 501and radio 502-1. Multi-radio host interface 702 accepts data blocks fromhost 501 via host data link 506. Multi-radio interface 702 thendetermines whether it should (1) transfer each data block tochannel-access controller 701 via path 711, if the data block is meantfor radio 502-1, or (2) relay the data block over to radio 502-2 vialink collateral radio data link 507. Multi-radio host interface 702accepts data blocks from channel-access controller 701 and transfersthem to host 501. In other words, multi-radio host interface 702provides multiple logical channel interfaces on a single physicalchannel interface to host 501. After reading this specification, it willbe clear to those skilled in the art how to make and use multi-radiohost interface 702.

Baseband controller 703 exchanges signals with channel-access control701 via path 712. It also exchanges signals with receiver 704-1 andtransmitter 705-1 via paths 713 and 714, respectively. In the receivedirection, baseband controller 703 accepts the demodulated signal fromreceiver 704-1 and converts the signal into a format that can be used bychannel-access controller 701. In the transmit direction, basebandcontroller 703 takes the signal from channel-access controller 701 andconverts the signal into a format that is ready for modulation to thetransmit frequency, the modulation being performed by transmitter 705-1.It will be clear to those skilled in the art how to make and usebaseband controller 703.

In addition to exchanging signals with baseband controller 703, receiver704-1 and transmitter 705-1 exchange signals with antenna switch 503 viapaths 510-1-1 and 510-1-2, respectively. Transmitter 705-1 provides partof the functionality of the physical layer of communication—that is,modulation of the baseband signals, representing data blocks, receivedfrom baseband controller 703 to characteristics consistent with theparticular air interface protocol supported by radio 502-1. Transmitter705-1 can accomplish modulation through an intermediate frequency (IF)section, or stage, and a radio frequency section. It then amplifies thesignal to be transmitted via a power amplifier section. Transmitter705-1 transmits the modulated and amplified signal over the air throughantenna switch 503 and antenna unit 504. Receiver 704-1 receives,amplifies, and demodulates signals from antenna switch 503 and antennaunit 504, providing the signals to baseband controller 703.Respectively, receiver 704-1 and transmitter 705-1 receives andtransmits signals at a radio frequency communications band, such as, forexample, the 2.4 GHz Industrial, Scientific, and Medical (ISM) band orthe 5.0 GHz ISM band. It will be clear to those skilled in the art howto make and use receiver 704-1 and transmitter 705-1.

Radio 502-1 communicates with radio 502-2 via collateral radio data link507, signaling link 508-1, and signaling link 508-2. Collateral radiodata link 507 serves to exchange data blocks between host 501 and radio502-2, in well-known fashion. In accordance with the illustrativeembodiment of the present invention, signaling link 508-1 and signalinglink 508-2 provide the signaling interface between radio 502-1 and radio502-2, conveying transmitting/receiving status and specifying control.Signaling link 508-1 provides inter-MAC messaging from radio 502-1 toradio 502-2. Similarly, signaling link 508-2 provides inter-MACmessaging from radio 502-2 to radio 502-1.

Signaling links 508-1 and 508-2 comprise a communication andcoordination protocol. Signaling links 508-1 and 508-2 also provide timesynchronization functions between radio 502-1 and 502-2 for the purposesof determining time intervals corresponding to transmit opportunitiesfor either air interface (i.e., the air interface served by radio 502-1and the air interface served by radio 502-2). These characteristics aredescribed below.

Signaling link 508-1 conveys a first set of signals from radio 502-1 toradio 502-2. In some embodiments, this first set of signals comprises afirst transmitting indication signal, a first receiving indicationsignal, and a first idle indication signal. The transmit indicationsignal indicates when radio 502-1 is transmitting signals over the air.The receive indication signal indicates when radio 502-1 is receiving(or attempting to receive) signals from over the air. The idleindication signal indicates when radio 502-1 is neither in transmit modenor in receive mode (but is still powered on). The idle indicationsignal, for example, can be used to indicate when radio 502-1 is in apower save mode, possibly an opportunity in time when radio 502-2 cancontrol the shared frequency band. It will be clear to those skilled inthe art how to determine which signal levels indicate what condition.

Signaling link 508-2 transfers a second set of signals from radio 502-2to radio 502-1. In some embodiments, this second set of signalscomprises a first transmit inhibit signal. The transmit inhibit signalspecifies that radio 502-2 is commanding radio 502-1 to inhibittransmitter 705-1 of radio 502-1. In an illustrative scenario, radio502-2 has time-critical information to transmit over the air and needsto “cut in” to radio 502-1's usage of the communications band. Use ofthe transmit inhibit signal in this scenario forces the radio frequencyand intermediate frequency sections of transmitter 705-1 (within radio502-1) out of transmit mode or turns off the power amplifier section orboth, whatever ensures that no signal is transmitted by transmitter705-1. It will be clear to those skilled in the art how to turn off thetransmitter 705-1 of radio 502-1 so that no signal is radiated over theair. It will be clear to those skilled in the art how to determine whichsignal levels indicate which conditions.

In some other embodiments, radio 502-2 also uses signaling link 508-2 tosend a polite request signal to radio 502-1 as part of the second set ofsignals. The polite request signal indicates to radio 502-1 that radio502-2 has a data block to transmit, but does not necessarily have tosend it at that moment. Correspondingly, radio 502-1 understands that itdoes not have to turn off its transmitter the moment it receives apolite request signal. The polite request signal can also be used toindicate level of urgency or importance of the data block requiringtransmission, the time by which the data block has to be transmitted(i.e., latency tolerance), or other time-sensitive characteristics ofthe data blocks. The particular usage of the polite request signaldepends on the relationship of the respective air interfaces of radios502-1 and 502-2. It will be clear to those skilled in the art how tocustomize the usage of the polite request signal. It will be clear tothose skilled in the art how to determine which signal levels indicatewhich conditions.

Radio 502-1 continually monitors the second set of signals sent onsignaling link 508-2. Radio 502-1 uses the signals to make decisions asto when to transmit, when not to transmit, and when to communicatestatus or control or both back to radio 502-2 along signaling link508-1.

In some embodiments, all signals sent across signaling links 508-1 and508-2 apply bi-directionally—that is, each signal described thus far canalso be sent in the direction opposite to what has been described.Signaling link 508-1 can also send, as the first set of signals, asecond transmit inhibit signal and a polite request signal. Furthermore,signaling link 508-2 can also send, as the second set of signals, asecond transmitting indication signal, a second receiving indicationsignal, and a second idle indication signal. This fully reciprocalsharing between radios 501-1 and 501-2 of status and control signals canbe used, for example, in applications where master control of theradios—functionality essentially residing in radio 502-1 in theillustrative embodiments—has to be reassigned to a different radio(e.g., radio 502-2, etc.).

FIG. 8 depicts a block diagram of wireless terminal 800 in accordancewith the fourth illustrative embodiment of the present invention.Wireless terminal 800 supports two distinct wireless air interfaceprotocols concurrently. The wireless protocols supported by wirelessterminal 800 can be, for example, 802.11 and Bluetooth. Wirelessterminal 800 comprises host 501, radio 502-1, radio 502-2, antennaswitch 503, and antenna unit 504, interconnected as shown. Radio 502-1comprises receiver 704-1, transmitter 705-1, and host interface 801-1.Radio 502-2 comprises receiver 704-2, transmitter 705-2, and hostinterface 801-2. Other elements constituting radios 502-1 and 502-2 havebeen depicted earlier and for clarity are not depicted in FIG. 8.

Each of host data links 802-1 and 802-2 is a peripheral bus providingsignaling, messaging, and control between those devices connected to thebus. It will be clear to those skilled in the art how to make and usethe bus constituting each of host data links 802-1 and 802-2. In theillustrative embodiment, host 501 is one such device connected to thebus, radio 502-1 is another device regarding host data link 802-1, andradio 502-2 is yet another device regarding host data link 802-2. Eachof radios 502-1 and 502-2 can interface with its bus mechanically, aswell as electrically, through a removable circuit card designed for suchan application. Examples of standardized busses include PCI, MiniPCI,and CardBus, all well known in the art. It will be clear to thoseskilled in the art how to make and use an interface that constituteshost data link 802-1 and an interface that constitutes host data link802-2.

Host interface 801-1 provides the interface between host 501 and radio502-1, in well-known fashion. Host interface 801-1 accepts data blocksfrom host 501 via host data link 802-1. Host interface 801-1 is alsoconnected to channel-access controller 701 (described earlier) in radio705-1 via a path equivalent to path 711 and accepts data blocks fromchannel-access controller 701, transferring them to host 501. Note thathost interface 801-1 is identical to multi-radio host interface 702,except that host interface 801-1 does not have to sort out data blocksfor or from radio 502-2. It will be clear to those skilled in the arthow to make and use host interface 801-1.

Host interface 801-2 provides the interface between host 501 and radio502-2, in well-known fashion. Host interface 801-2 accepts data blocksfrom host 501 via host data link 802-2. Host interface 801-2 is alsoconnected to channel-access controller 701 (described earlier) in radio705-2 via a path equivalent to path 711 and accepts data blocks fromchannel-access controller 701, transferring them to host 501. It will beclear to those skilled in the art how to make and use host interface801-2.

FIG. 9 depicts a timing diagram of an exemplary communication sequencefor receiver 704-1, transmitter 705-1, and transmitter 705-2, inaccordance with the illustrative embodiment of the present invention.This timing diagram serves to illustrate the operation of radio 502-1and radio 502-2 in accordance with the fifth illustrative embodiment ofthe present invention. For illustrative purposes, radio 502-1 operatesin accordance with the 802.11 air interface protocol and radio 502-2operates in accordance with the Bluetooth air interface protocol. Itwill be clear, however, to those skilled in the art that radios 502-1and 502-2 can operate in accordance with other protocols.

FIG. 9 shows two sequences related to transmitter 705-1. Signal stream901 represents the input signal into transmitter 705-1 provided on path714, and signal stream 902 represents what actually is transmitted bytransmitter 705-1 (i.e., the transmitter's “output” on path 510-1-2).The distinction between transmitter 705-1's input and its output will bemade clear below.

The first frame intended for transmission is frame 911, provided totransmitter 705-1. Since transmitter 705-1 is active, transmitted frame921 (corresponding to frame 911) is equivalent to frame 911 (i.e., allof frame 911 reaches antenna unit 504), except for the fact that frame911 is an unmodulated signal while frame 921 is modulated.

The next transmission in the sequence is acknowledgement frame 931 ofsignal stream 903, which is received, in well-known fashion, by receiver704-1 from the station to which frame 921 was directed.

The next frame intended for transmission in the sequence is frame 912,provided to transmitter 705-1. As shown in FIG. 9, at time to duringtransmission of corresponding frame 922, transmitter 705-2 transmits, aspart of signal stream 905, lower latency-tolerant packet 951 (e.g., asynchronous connection-oriented [SCO] packet, etc.), whilesimultaneously, the transmit inhibit signal (described earlier),represented by signal 906, is set high. The transmit inhibit signal isprovided on signaling link 508-2.

For the purposes of discussion of the illustrative embodiments of thepresent invention, it is assumed that setting a signal high indicatesthat control is being exercised and that resetting a signal lowindicates that control is no longer being exercised by the particularsignal line. It will be clear to those skilled in the art how toindicate control in a way that is suitable to the particular design.

The transmit inhibit signal indicated to radio 502-1 and, moreparticularly, to transmitter 705-1, ultimately controls the signalradiated by radio 502-1. In order to suppress radiation of a signal, itmight be necessary to turn off or turn low the power amplifier and theRF/IF sections of transmitter 705-1, as described earlier. It will beclear to those skilled in the art how to suppress output fromtransmitter 705-1.

Setting the transmit inhibit signal prevents the remainder of frame 912from reaching antenna unit 504, as shown by frame 922. When transmitter705-2 completes lower latency-tolerant packet 951, the transmit inhibitsignal resets low, thereby allowing input to transmitter 705-1 to onceagain reach antenna unit 504. The transmit inhibit signal, incombination with any intermediate logic gates required to format thecontrol signal actually provided to transmitter 705-1, acts as apreemption signal that effectively suppresses output from transmitter705-1 during transmitter 705-2's transmissions, thereby avoidinginterference.

Meanwhile, transmitter 705-1, unaware that frame 912 did not fully reachantenna unit 504, waits for an acknowledgement in accordance withautomatic repeat request (ARQ) error correction, as is well understoodin the art. Since frame 912 was effectively interrupted, transmitter705-1 does not receive such an acknowledgement, and, after a timeout inaccordance with the protocol, retries frame 912 (in the form of frame913.) As illustrated in FIG. 9, as long as Bluetooth packet 951 is keptsufficiently short, transmitter 705-1 is no longer suppressed bytransmitter 705-2 when transmitting frame 913. Consequently, frame 913in its entirety reaches antenna unit 504 (shown by frame 923), andreceiver 704-1 subsequently receives acknowledgement 932. Recalling the802.11/Bluetooth nature of the example depicted by FIG. 9, the IEEE802.11 ARQ error correction thus automatically compensates forsufficiently-short Bluetooth interruptions (i.e., interruptions that arenot “fatal”) without any changes to the protocols.

It will be clear to those skilled in the art that ARQ error correctionwill also automatically compensate for sufficiently-short transmissionsfrom transmitter 705-2 of radio 502-2 that overlap receiver 704-1'sreceiving of data. In addition, it will be clear to those skilled in theart how to make and use alternative embodiments of the present inventionfor protocols that use other methods of error correction (e.g., forwarderror correction, etc.) In the case of forward error correction, forexample, the interruption of a transmission is not fatal as long as theinterruption is kept short enough so that the number of suppressed bitsis below the particular error correction threshold.

So far throughout the exemplary sequence depicted in FIG. 9, radio 502-1has been active, as shown by the “low” value of signal 904,corresponding to the first idle indication signal of radio 502-1, whichis provided by signaling link 508-1 to radio 502-2. Afteracknowledgement frame 932, radio 502-1 enters power-save (i.e., idle)mode, as shown in FIG. 9 by the transition of first idle indicationsignal (signal 904) from low to high. Transmitter 705-2, upon detectingthis transition, takes advantage of this situation by transmittinghigher latency-tolerant packet 952 (e.g., an asynchronousconnection-less [ACL] packet, etc.). Thus, instead of preemptingtransmitter 705-1, as is done for transmissions with a lower latencytolerance (e.g., transmission 951, etc.), transmitter 705-2 waits forradio 502-1 to enter power-save mode before initiating transmissionswith a higher latency tolerance (e.g., 952, etc.).

When radio 502-1 exits power-save mode (i.e., “wakes up”), it executes a“warm-up sequence” before transmitting any frames, as is well known inthe art. If radio 502-1 happens to wake up while transmitter 705-2 isstill transmitting, radio 502-2, which detects that radio 502-1 hasawakened, terminates transmitter 705-2's transmissions. As will be clearto those skilled in the art, the warm-up sequence of radio 502-1,operating in the example in accordance with the Bluetooth protocol,gives transmitter 705-2 plenty of time to gracefully terminate anyin-progress transmissions. Any “left-over” information that transmitter705-2 was unable to transmit before radio 502-1 awoke is queued for thenext time that radio 502-1 enters power-save mode; this postponement isnot problematic since, by definition, the information has a higherlatency tolerance. If, instead, this information had a lower latencytolerance, transmitter 705-2 would have previously preempted transmitter705-1, as described above.

FIG. 10 depicts a block diagram of radio 502-1 in another variation ofthe third illustrative embodiment of the present invention. FIG. 10 issimilar to FIG. 7, except that the signaling links between radios 502-1and 502-2 are interfaced directly to multi-radio host interface 1002.Consequently, channel-access controller 1001, multi-radio host interface1002, and path 1005 are different from channel-access controller 701,multi-radio host interface 702, and path 705, respectively.

Channel-access controller 1001 provides the medium access controlfunctionality for communicating in accordance with a first air interface(e.g., 802.11, Bluetooth, etc.). In this regard, it provides the samefunctionality as channel-access controller 701. It accepts host datafrom multi-radio host interface 1002 via path 1005. It provides datafrom host 501 to baseband controller 703 via path 712 for preparationfor transmission. Channel-access controller 1001 also provides datareceived over the air from baseband controller 703 via path 712 to host501 through path 1005 and multi-radio host interface 1002.Channel-access controller 1001 can track whether it has control or radio502-2 has control of the communications band at any given moment.Consequently, channel-access controller 1001 can control antennaswitching at antenna switch 503 via path 511-1. Alternatively,channel-access controller 1001 can operate uninformed of the status ofradio 502-2.

Channel access controller 1001 can pass to radio 502-2 via signalinglink 508-1 information representative of receiver 704-1 and transmitter705-1, received through path 1006. Channel access controller 1001 canpass to receiver 704-1 and transmitter 705-1 via path 1006 informationrepresentative of radio 502-2, received through signaling link 508-2. Itwill be clear to those skilled in the art how to make and usechannel-access controller 1001.

In accordance with the illustrative embodiment of the present invention,multi-radio host interface 1002 provides the interface between host 501and radio 502-1. Multi-radio host interface 1002 accepts data blocksfrom host 501 via host data link 506. Multi-radio host interface 1002then determines whether it should (1) transfer each data block tochannel-access controller 1001 via path 1005, if the data block is meantfor radio 502-1, or (2) relay the data block over to radio 502-2 vialink collateral radio data link 507. Multi-radio host interface 1002accepts data blocks from channel-access controller 1001 and transfersthem to host 501. In other words, multi-radio host interface 1002provides multiple logical channel interfaces on a single physicalchannel interface to host 501. After reading this specification, it willbe clear to those skilled in the art how to make and use multi-radiohost interface 1002.

Multi-radio host interface 1002 terminates one end of collateral radiodata link 507, as well as signaling links 508-1 and 508-2. Collateralradio data link 507 and signaling links 508-1 and 508-2 can be differentinterfaces to radio 502-2 physically, or they can be the same interface.It will be clear to those skilled in the art how to combine collateralradio data link 507 and signaling links 508-1 and 508-2 into oneinterface. Each of the interfaces with radio 502-2 can be a serialinterface or a parallel interface. It will be clear to those skilled inthe art how to make and use a serial or parallel interface. If one ormore of collateral radio data link 507 and signaling links 508-1 and508-2 are serial, the serial interface characteristics can compriseSERDES, IEEE1394 style data/strobe encoding, or RFF(2,5) coding, inwell-known fashion.

The signaling information that is exchanged between radio 502-1 and502-2 can be represented in any of a variety of formats. Signals fromradio 502-1 can be communicated to radio 502-2 along signaling link508-1 via a single high or low electrical signal, one signal value perstate, in well-known fashion. For example, when radio 502-1 wants toindicate that it is transmitting, it can set the transmitting indicationsignal line to “high” and maintain that signal value for as long asradio 502-1 is in the transmitting state. When radio 502-1 stopstransmitting, it can reset the transmitting indication signal line to“low”, and maintain that signal value for as long as radio 502-1 is nottransmitting. Similarly, signals from radio 502-2 can be communicated toradio 502-1 along signaling link 508-2 via a single high or lowelectrical signal, one signal value per state, in well-known fashion.

Alternatively, signals can be communicated between radio 502-1 and radio502-2 via a packet format (i.e., a format using blocks of data torepresent information), as opposed to using individual electrical signallevels to directly represent information. For example, when radio 502-1wants to indicate that it is transmitting, it can prepare and transfer apacket message to radio 502-2 indicating “transmitting” when the statechange from “not transmitting” to “transmitting” occurs. When radio502-1 stops transmitting, it can prepare and transfer a packet messageto radio 502-2 indicating “not transmitting” when the state change from“transmitting” to “not transmitting” occurs. The packet message alsospecifies the type of message being sent, such as control (e.g.,transmit inhibit, etc.), status (e.g., idle indication, etc.), or hostinterface-related (e.g., data message for radio 502-2 from host 501,etc.). The packet format can be transferred in full-duplex,bidirectional fashion between radios 502-1 and 502-2. It will be clearto those skilled in the art how to make and use a packet format toconvey signals and to do so in full-duplex, bidirectional fashion.

FIG. 10 depicts signaling link 508-1 as comprising M lines and signalinglink 508-2 as comprising N lines. This is for illustrative purposesonly, since signaling links 508-1 and 508-2 can be combined withcollateral radio data link 508 in practice. The values for M and Ndepend on several factors, including (in no particular order):

-   -   1. Whether each of signaling link 508-1 and 508-2 is a serial or        parallel interface;    -   2. How wide the parallel interface is;    -   3. If communication is full-duplex, bidirectional;    -   4. If the information is sent in packet format; and    -   5. If collateral radio data link 507, signaling link 508-1, and        signaling link 508-2 are combined into one interface.        Values for M and N are determined in well-known fashion. If the        three links are combined into one serial interface that is        full-duplex, bidirectional with packet format, the number of        lines required by that interface is as little as two, consistent        with the notion of low cost, low complexity.

It is to be understood that the above-described embodiments are merelyillustrative of the present invention and that many variations of theabove-described embodiments can be devised by those skilled in the artwithout departing from the scope of the invention. It is thereforeintended that such variations be included within the scope of thefollowing claims and their equivalents.

1. An antenna switching system comprising: a first transceiver of aplurality of transceivers; a first processor configured to process anapplication stored in memory; a second transceiver of the plurality oftransceivers electrically connected between the first processor and thefirst transceiver, the second transceiver configured to relay messagesfrom the first processor to the first transceiver; a switch configuredto connect a plurality of transceivers to at least one antenna; and asecond processor configured to control the connection of the switch toone or more of the first and second transceivers.
 2. The system of claim1, wherein at least one of the plurality of transceivers is configuredto transceive on a transmission medium with a first protocol.
 3. Thesystem of claim 2, wherein at least one of the plurality of transceiversis configured to transceive on a transmission medium with a secondprotocol.
 4. The system of claim 3, wherein the second transceiver isconfigured to receive data blocks from the first processor and transmitthe data blocks on a data bus to the first transceiver.
 5. The system ofclaim 4, further comprising at least one antenna electrically connectedto the switch.
 6. The system of claim 3, wherein at least one of thefirst and second protocols is Bluetooth.
 7. The system of claim 3,wherein at least one of the first and second protocols is IEEE 802.11.8. The system of claim 1, wherein the second processor is configured toreceive an idle indication signal from one of the first and secondtransceivers.
 9. The system of claim 1, wherein the second processor isconfigured to transmit a transmit inhibit signal to one of the first andsecond transceivers.
 10. The system of claim 1, wherein the antennaswitching system is included in a wireless radio.
 11. A method ofswitching of at least one antenna: providing at least a firsttransceiver and a second transceiver of a plurality of transceivers;providing a signal from a first processor to a first transceiver of theplurality of transceivers electrically connected between the firstprocessor and the second transceiver; determining whether the signal isto be transmitted by the first transceiver or the second transceiver;relaying the signal from the first transceiver to the second transceiverif the determination is made that the data is to be transmitted by thesecond transceiver; and switching an antenna switch to electricallyconnect one of the first and second transceivers to at least one antennaof a plurality of antennas, the connected transceiver corresponding tothe determination of whether the signal is be transmitted by the firsttransceiver or the second transceiver.
 12. The method of claim 11,further comprising configuring the first transceiver of the plurality oftransceivers to transceive with a first protocol and the secondtransceiver of the plurality of transceivers to transceive with a secondprotocol.
 13. The method of claim 12, further comprising transmittingwherein at least one of the plurality of transceivers is configured totransceive on a transmission medium with a second protocol.
 14. Themethod of claim 11, further comprising configuring the first transceiverto receive the signal from the first processor and transmit the signalon a data bus to the second transceiver.
 15. The method of claim 11,further comprising transmitting the signal through the at least oneantenna.
 16. The method of claim 12, wherein at least one of the firstand second protocols is Bluetooth.
 17. The method of claim 12, whereinat least one of the first and second protocols is IEEE 802.11.
 18. Themethod of claim 11, further comprising receiving by a second processoran idle indication signal from one of the first and second transceivers.19. The method of claim 18, further comprising switching the antennaswitch corresponding to the reception of the idle indication signal. 20.The method of claim 11, further comprising transmitting by a secondprocessor a transmit inhibit signal to one of the first and secondtransceivers, the transmit inhibit signal corresponding to the switchingof the antenna switch.
 21. A radio comprising: a transmitter and areceiver for communicating according to a first wireless protocol; achannel-access controller configured to generate antenna switch controlsignals to selectively connect an antenna to the transmitter andreceiver; and a host interface for receiving a data block, configuredto: determine whether to transmit the data block with the transmitter orto forward the data block to a collateral radio; in response todetermining to transmit the data block with the transmitter, providingthe data block to the channel-access controller; and in response todetermining to forward the data block, forwarding the data block to thecollateral radio.
 22. The radio of claim 21, wherein the collateralradio is configured to transceive on a second protocol.
 23. The radio ofclaim 21, further comprising at least one antenna switch electricallyconnected to the radio.
 24. The radio of claim 23, further comprising atleast one antenna electrically connected to the antenna switch.
 25. Theradio of claim 21, wherein at least one of the first and secondprotocols is Bluetooth.
 26. The radio of claim 21, wherein at least oneof the first and second protocols is IEEE 802.11.
 27. The radio of claim21, wherein either the channel-access controller or the host interfaceis configured to receive an idle-indication signal.
 28. The radio ofclaim 21, wherein either the channel-access controller or the hostinterface is configured to transmit a transmit-inhibit signal.
 29. Aradio comprising: a channel-access controller configured to transmit adata block, and generate an antenna switch control signal responsive tohaving the data block provided; and a host interface configured to:receive the data block from a host interface bus; determine whether totransmit the data block with a transmitter or to forward the data blockto a collateral radio; in response to determining to transmit the datablock with the transmitter, provide the data block to the channel-accesscontroller; and in response to determining to forward the data block,forward the data block to the collateral radio.
 30. The radio of claim29, wherein the collateral radio is configured to transceive on a secondprotocol.
 31. The radio of claim 29, further comprising at least oneantenna switch electrically connected to the radio.
 32. The radio ofclaim 31, further comprising at least one antenna electrically connectedto the antenna switch.
 33. The radio of claim 29, wherein either thechannel-access controller or the host interface is configured to receivean idle-indication signal.
 34. The radio of claim 29, wherein either thechannel-access controller or the host interface is configured totransmit a transmit-inhibit signal.
 35. A method comprising: receiving apacket with a first transceiver; a host interface within the firsttransceiver determining whether to transmit the packet with the firsttransceiver operating on a first wireless protocol or to forward thepacket to a collateral transceiver operating on a second wirelessprotocol; in response to determining to transmit the packet with thefirst transceiver, a channel access controller within the firsttransceiver generating a switching control signal for switching anantenna switch; and in response to determining to forward the packet,the host interface forwarding the packet to the collateral transceiver.36. The method of claim 35, further comprising transmitting the packetthrough at least one antenna.
 37. The method of claim 35, wherein atleast one of the first and second protocols is Bluetooth.
 38. The methodof claim 35, wherein at least one of the first and second protocols isIEEE 802.11.
 39. The method of claim 35, further comprising receiving anidle indication signal by one selected from the group consisting of thechannel-access controller and the host interface.
 40. The method ofclaim 35, further comprising transmitting a transmit inhibit signal byone selected from the group consisting of the channel-access controllerand the host interface.
 41. A radio comprising: means for generating anantenna switch control signal responsive to having the data blockprovided; means for receiving the data block from a host interface bus;means for determining whether to transmit the data block or to forwardthe data block, means for transmitting the data block, in response todetermining to transmit the data block; and means for forwarding thedata block, in response to determining to forward the data block. 42.The radio of claim 41, further comprising means for transceiving on asecond protocol.
 43. The radio of claim 41, further comprising means forswitching an antenna.
 44. The radio of claim 41, further comprisingmeans for receiving an idle-indication signal.
 45. The radio of claim41, further comprising means for transmitting a transmit-inhibit signal.